Hydrological feedbacks on peatland CH4 emission under warming and elevated CO2: A modeling study

Fenghui Yuan, Yihui Wang, Daniel M. Ricciuto, Xiaoying Shi, Fengming Yuan, Thomas Brehme, Scott Bridgham, Jason Keller, Jeffrey M. Warren, Natalie A. Griffiths, Stephen D. Sebestyen, Paul J. Hanson, Peter E. Thornton, Xiaofeng Xu

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

Peatland carbon cycling is critical for the land–atmosphere exchange of greenhouse gases, particularly under changing environments. Warming and elevated atmospheric carbon dioxide (eCO2) concentrations directly enhance peatland methane (CH4) emission, and indirectly affect CH4 processes by altering hydrological conditions. An ecosystem model ELM-SPRUCE, the land model of the E3SM model, was used to understand the hydrological feedback mechanisms on CH4 emission in a temperate peatland under a warming gradient and eCO2 treatments. We found that the water table level was a critical regulator of hydrological feedbacks that affect peatland CH4 dynamics; the simulated water table levels dropped as warming intensified but slightly increased under eCO2. Evaporation and vegetation transpiration determined the water table level in peatland ecosystems. Although warming significantly stimulated CH4 emission, the hydrological feedbacks leading to a reduced water table mitigated the stimulating effects of warming on CH4 emission. The hydrological feedback for eCO2 effects was weak. The comparison between modeled results with data from a field experiment and a global synthesis of observations supports the model simulation of hydrological feedbacks in projecting CH4 flux under warming and eCO2. The ELM-SPRUCE model showed relatively small parameter-induced uncertainties on hydrological variables and their impacts on CH4 fluxes. A sensitivity analysis confirmed a strong hydrological feedback in the first three years and the feedback diminished after four years of warming. Hydrology-moderated warming impacts on CH4 cycling suggest that the indirect effect of warming on hydrological feedbacks is fundamental for accurately projecting peatland CH4 flux under climate warming.

Original languageEnglish
Article number127137
JournalJournal of Hydrology
Volume603
DOIs
StatePublished - Dec 2021

Funding

The authors are grateful for financial and facility support from San Diego State University. Financial assistance was partially provided by the SPRUCE and NGEE Arctic projects, which are supported by the Office of Biological and Environmental Research in the Department of Energy Office of Science. This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research. Oak Ridge National Laboratory is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. The SPRUCE experiment is a collaborative research effort between ORNL and the USDA Forest Service. The contribution of SDS was supported by the Northern Research Station of the USDA Forest Service.

FundersFunder number
NGEE
Office of Biological and Environmental Research in the Department of Energy Office of Science
SPRUCE
U.S. Department of Energy
Office of Science
Biological and Environmental Research
Oak Ridge National LaboratoryDE-AC05-00OR22725
U.S. Forest Service
San Diego State University

    Keywords

    • Elevated carbon dioxide
    • Hydrology
    • Methane
    • Model
    • Peatland
    • Warming

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